
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>滚动条下拉DIV固定在头部不动</title>
<script type="text/javascript" src="http://libs.baidu.com/jquery/1.9.1/jquery.min.js"></script>
<style>
*{padding:0;margin:0;}
.ab{ width:100%; background-color:#eee; height:250px; text-align:center; line-height:250px;}
.bc{ width:100%; background-color:#eee; text-align:center; text-align:center; color:#fff; font-size:24px; background-color:#060;}
.pf{ width:100%; height:50px; background-color:#C00; text-align:center; line-height:50px; color:#fff;}

/*---------------------漂浮导航---------------------------*/
html{ _background-image:url(about:blank); _background-attachment:fixed;/** 防止 ie6 抖动 **/}
.float{ position:fixed; z-index:999999; top:0px;}
* html .float{ position:absolute; _top:expression(documentElement.scrollTop-0);}
</style>

</head>

<body>
<div class="ab">第一版块</div>
<div class="pf">漂浮内容</div>
<script type="text/javascript">
window.onscroll=function(){
	if ($(document).scrollTop() > 250)
	{
		//$("#pf_nav").show();
		$(".pf").addClass('float');
	}else{
		//$("#pf_nav").hide();
		$(".pf").removeClass('float');
	}
}
</script>
<div class="bc">
  <p>
    <script language="javascript">
for(i=0;i<50;i++){
	document.write(i+"<br />");
}
  </script>
  </p>
</div>
</body>
</html>
